Stair climbing wheel chair



sept. 17, 1963 3,104,112

J. W. CRAIL STAIR CLIMBING WHEEL CHAIR Filed July 2, 1962 4@ Hb 44INVENToR. 4 I3 JESSE W. CRA/L United States Patent 3,104,112 STAIRCLHVIBING WHEEL CHAR .lesse W. Crail, 38692 Edenhurst Ave., Los Angeles,Calif. Filed July 2, 1962, Ser. No. 296,693 4 Claims. (Cl. 28d- 5.2)

This invention relates generally to stair climbing wheel chairs, andmore particularly to such a wheel chair in which auxiliary front wheelscan be lowered land releasably locked into stair climbing position by abackward swinging linkage means, in combination with an adjustablepressure driving means which can be temporarily retracted for operationof said back-ward swinging linkage means.

A great variety of wheel chairs have been designed for the convenienttransport of persons who suffer from some disability which prevents themfrom walking for an extended period of time, or from walking at all. Alarge and important category of wheel chair designs include a means oflocomotion in which the use-r himself supplies the driving power. Manyhandicapped persons are handicapped only with respect to walking, Iandare equal to or superior to unhandicapped persons in the strength anddexterity of their arms and hands. Wheel chairs have, therefore, beenydesigned with manually operated crank means, reciprocating drive leversand the like. Usual-ly, such occupant-operated chairs are also providedwith handles at the back so that they can be pushed by an attendant whenthe occupant does not wish to make the physical exertion required whenhe is supplying his own power of locomotion.

However, many healthy handicapped persons do not want to rely upon thepresence of an attendant, and prefer to travel alone almost as freely4as if they were able to walk as well as the average unhandicappedperson. Many excellent wheel chairs heretofore known have provided thehandicapped person with complete mobility as long as he has restrictedhimself to horizontal or nearly horizontal services. Up t the presenttime, no wheel chair capable of climbing stairs has come into widespreaduse.

Various stair climbing wheel chairs have been proposed, but all havesuffered from some major limitation which made them unsuited orimpractical for most wheel chair users. Thus, some stair climbing wheelchair designs have involved such extensive and massive mechanism thatonly the most athletic of wheel chair users could apply the muscle powerneeded to operate them `on stairs, or even on horizontal services. Otherstair climbing wheel chairs have required electrical or gasoline powermeans.

Almost all widely used rwheel chairs can be folded into a collapsedposit-ion. Experience has proven that this feature is a very importantone, not merely for convenience in storage when the chair is not in use,but also for transporting the chair when the occupant travels byautomobile or by public transportation means, or when the occupantwishes to sit in a theater seat and tempor-arily store the chair in aspace small enough to prevent it from blocking the passage of otherpeople. Some previously proposed stair climbing Wheel chairs haveinvolved a construction inconsistent with collapsibility; consequently,`such designs have never been accepted into general use.

It is an important object of the present invention to pro-vide a stairclimbing Iwheel chair construction which can be used in folding wheelchairs.

It is another important object yof the present invention to provide awheel chair in which the stair climbing mechanism is light, very strong,and readily operable on stairs by a person of average strength, withoutthe aid of any auxiliary motor means.

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It is important to note that in the achievement of these objects, it hasbeen necessary to provide safety means to prevent any runaway of thewheel chair during the stair climbing operation. Also, the manual drivemechanism used during stair climbing has been made retractable so thatordinary hand rings can be used when traveling on the level.

Still another important feature of the present invention, which makes itsubstantially superior to previously known stair climbing designs, isthat the wheel chair occupant :is able to convert his Wheel chair intostair climbing position, while at the same time lifting the weight ofhimself land his chair, by means of the linkage which enables him toapply the maximum strength of his arms.

The objects and `advantages of the invention are achieved by means of =alconstruction which will best be understood from -a description of onepreferred specific embodiment, which is illustrated in the accompanyingdrawings, in which:

FIGURE 1 is la right side elevational view of a Wheel chair constructedaccording to the invention, with the stair climbing mechanism retractedand out of use, so that the chair can be conveniently moved over a'horizontal surface by the occupant;

.FIGURE 2 is a right side elevational view of the chair of FIGURE l, butwith the stair climbing mechanism lowered into stair climbing position;

FIGURE 3 is a plan View of the wheel chair as viewed in FIGURE l, butshowin-g the left manual driving wheel rotated into ia retractedposition;

FIGURE 4 is a perspective view of a fragmentary portion of the wheelchair, yas seen from a point looking at the left rear vertical framemember, but with portions of the chair disassembled to revealconstruction which would otherwise be concealed; and

FIGURE 5 is a detail perspective view of a latch employed for lockingthe stair climbing mechanism in retracted position'as illustrated inFIGURE l.

In the drawings, the wheel chair, indicated generally by the numeral 10,is seen to have `all its essential parts mounted on a folding metalframe indicated generally by the numeral r11, and comprised :of rightand left side frame members 12 and 13, respectively, best seen in theplan View of FIGURE 3, and folding cross-bar members 14 and 15.

The `side frame members 12 and 13 are substantially identical inconstruction. 'Ihe fra-mes may be of standard types used in wheel chairsIwell known in presently used designs. For example, chrome plated steeltubing welded into the shape shown, `or any convenient equivalent shapemay be employed. In the particular embodiment illustrated, right sideframe 12 (and also left side frame 13) is comprised of front and rearvertical members 20 and 21, an-d three horizontal members 22, 23, and24, all l welded together into an integral side frame structure. Upperhorizontal member 22 serves as an arm rest; middle horizontal member 23-is a seat frame member; and the lower horizontal member 24 is a basemember for the side frame 12.

As seen in FIGURE 3, the folding crossbar members '14 and 15 serve tohold the Iside frame members 12 and 13 parallel to each other and spacedfrom each other a ldistance corresponding .to the width yof the wheelchair seat.

'Ifhe novelty of the present invention does not reside in the particularmeans by which folding is achieved, or in the particular constructionyof folding cro-ssbars 14 and I15. The novelty resides in a combinationwhich provides a stair climbing wheel chair, and in a stair climbingmechanism which, unlike many previously known stair are rotatablyconnected by sleeves 33 and 34 on seat frame member 23 and base framemember 24, respectively, of the side frames `12 and 13. It will beunderstood, however, that any suitable folding mechanism may be usedbetween the side frames 12 and 13 for holding them in erected positionfor wheel chair use, or folded together for storage.

The plan view of FIGURE 3 reveals that a readily foldable fabric seat4t) and fabric back 41 (shown partially broken `away to illustrate thefolding crossbars 14 and 15 in plan) are stretched between the sideframes 12 and 13. Also, as is conventional in most folding wheel chairs,each of the side frames 12 and 13 is provided at the forward portionwith foot support brackets 42 and 43, which support folding foot rests44 and 45, respectively. Push handles 46 and 47 are provided at the rearof the wheel chair 1t? on the upper ends of rear vertical members 21.

The main wheels provided for rolling of the wheel chair are not thetwenty-five inch hard-tire wheels usually found in most of the foldinglwheel chairs available on the market at the present time, but arelarger, and use pneumatic tires. The main wheels, right and left mainwheels 50 and 51, respectively, lare rotatably mounted on right and leftstub wheel shafts 52 land 53, respectively. Tlie main wheels areprovided with hand-propulsion rings 50a and 51a seen in'pl-an in FIG. 3,and partially broken away in FIGS. l and 2 for purposes of illustrationof the stair climbing mechanism. The stub shafts 52 and 53 areintegrally mounted on the rear verticals 21 of right and left sideframes 12 and 13, usually just a short space below the level of the seatframe members 23. Main wheels 50 yand 51 `are usually of a light spokeand rim construction with inflated rubber tires 54. Also, the mainwheels are usually of relatively large diameter, being between thirtyinches by two inches in the specific embodiment, so as to provide thewheel chair user with a smooth rolling transport despite irregularitiesin ground surface, and also, so that an attendant may push or pull thewheel chair up the average stairway, lwhich usually has treads andrisers of about ten inches and seven inches, respectively.

The forward part of the wheel chair 10 is provided with rolling supportby right yand left identical swiveling casters, typically illustrated byright caster 60. Preferably, the two swiveling casters 60 are mountedunder the forward portions of side frames 12 and 13, respectively.

It has been common in previously known wheel chairs to provide theoccupant with crank-operated friction wheels with `which to achieveself-locomotion. Right and left friction lwheels 65 and 66, and theirassociated cranks 67 and 63, are illustrated as mounted on arm restmember 22 of the side frames 12 'and 13. They are adapted, when indriving position as illustrated in FIG- URES 1 `and 2 for right`friction wheel 65, to bear against the tread of tires 54, 'and therebyenable an occupant to drive the `niain wheels G and 51 by manualrotation of cranks 67 and 68. However, the friction wheels 65 and 66 inthe illustrated specic embodiment of the present invention are mountedin a novel manner in order to coact with other components of theinventive combination which makes it possible t0 use the wheel chair ofthe invention for self-locomotion Iup a stairway.

It is `a much preferred form of the present invention to make thefriction wheels 65 and 66 retractable from a driving position `asillustrated for right friction wheel in FIGURES l, 2, and 3, and forleft friction wheel in FIGURE 4, on the one hand, and, on the otherhand, a retracted position illustrated in FIGURE 3 for left frictionwheel 66. Also, `as will be described hereinafter, it

l is much preferred to provide the right and left friction wheels withadjustable drive pressure means.

Before proceeding to a detailed description of the `preferred form ofretractable friction wheels 65 and 66, the principal stair climbingmechanism will be described. The wheel chair 10 provided with right andleft stair climbing wheels 70 and 71, which [are mounted at the forwardends of arms 72 and 73, on stub shafts 74 `and 75, respectively.

Arms 72 and 73 are pivotally rmounted to side frames 12 and 13,preferably in a simple and convenient way by being mounted 'on mainwheel stub shafts 52 and 53, inboard of main wheels 5t) `and 51. Thus,the stair climbing wheels 7G and 71 may be selectively swung between 'aretracted position, as illustrated in FIGURE l, when not in use; and astair climbing position, as illustrated in FIGURE 2, when lowered forstair climbing use.

The right and left arms 72 `and 73 may be braced to each other to form arigid unitary frame structure by means of transverse brace 75, which is`preferably hinged at the ends and middle as indicated by hinges 76, soas to be foldable with the wheel chair 10. A standard type of bolt latch77, or any convenient type of releasable locking means is provided onthe transverse brace 75 to lock it into unfolded position.

Also, as illustrated in FIGURE 5, a retractable spring latch 78 ismounted on the forward side of side frame 12 so yas to providereleasable means for locking the arms 72 and 73 in the raised positionillustrated in FIGURE l.

The 4arms 72 and 73 are pulled downward into the stair climbing positionof FIGURE 2 by means of right and left linkages, 8i) and 81,respectively, which are pivotally mounted at fulcrurns 82 vand 83,respectively, in relatively massive fulcrum support `bars 84 and S5,respectively, which are integral parts of right and left side frames,I12 and 13, respectively.

The linkages Si) and 81 lare identical, and are constructed asillustrated for linkage 8i) in FIGURES l and 2. A bell crank 86 ismounted in the fulcrum S2. At its lower end, it is connected by pivotconnection 87 to an arm link 88, which is in turn pivotally connected at89 to arm 72. A locking stop 90 is Welded to the `upper end of arm link8S, so that it forms a rigid brace for arm 72 when the linkage 80 ispulled into the position illustrated in FIGURE 2.

Preferably, the upper end of valve crank 86 is provided with a foldinglever ram 95, hinged to the bell crank at 96. This folding nature makesit possible to fold the lever downward and out of the way of thefriction wheels 65 'and 66, when the wheel chair 10 is travelinghorizontally, and the stair climbing apparatus is out of use, asillustrated in FIGURE l.

Although the operating levers 95 could be formed to by-pass the cranks67 and 68, while the latter are in their normal outboard position, it ismuch preferred to make friction wheels 65 and 66 retractable, asillustrated for friction wheel 66 in FIGURE 3, by means to be describedhereinafter, so that the seated occupant of rwheel chair 10 will have amaximum of leverage with a minimum of reach for converting fromhorizontal travel position of FIGURE 1 tto the stair climbing positionof FIGURE 2.

In FIGURE 4, the arch of movement of the lever 95 is illustrated by thearrow 100. Also, it vwill ,be seen that a catch 101 is welded to theoutboard side of the arm member 22 so as to catch lever arm 95 andretain the linkage v81 in stair climbing disposition. An identicalconstruction is provided yfor the right side frame 12.

FIGURES 3 and 4 illustrate retraction and adjustment for the frictionwheels 65 and 66. It will be understood that the crank 68 has `beenremoved from the friction wheel 66 in FIGURE 4, in order `to betterillustrate the vertical adjustment of friction wheel 66. As seen in FIG-URE 4, friction wheel 66 carries an integral crank shaft 110, which isjournalled in an inverted adjustable yoke 1,11. Yoke 111 is verticallyadjustable within an outer yoke 112, the sides of which are provided-with vertical slots 113 -to permit the vertical adjustment of frictionWheel shaft 110.

Outer yoke 112 is welded integrally to a sleeve 114,

lwhich is rotatable on arm member 22, between an outboard ldrivingposition (as illustrated for rig-ht friction wheel 65 in FIGURE 3) andan inboard retracted po- -sition (as illustratedl yfor left frictionwheel 66 in F-IG- 'URE 3) to permit full swing of lever 95 .along thearc 'indicated in FIGURE 4 by double arrow 100, for purposes of loweringarms 72 and 73 to stair climbing position illustrated in FIGURE 2. Alatch 115 is provided for releasably locking the sleeve 114 in driveposition.

Vertical adjustment of the drive wheels 65 and 66 is accomplished bymeans illustrated for drive wheel 66 in FIGURE 4. A smallv adjustmentcrank 120, with la threaded vertical shaft 121, is received in athreaded bore 122 in the upper portion of outer yyoke 112, so that roptation of adjustment crank 120 can be used to lforce its lower endagainst the upper portion of inner yoke 111,

thereby driving it downward into greater pressure of en- `position .forproviding safety against accidental runaway.

As seen in FIGURE l, `a ratchet wheel 131 is rotatable integral withmain Wheel 50 on right main wheel stub shaft 52, ratchet Wheel 131 beingformed 'with teeth 131a beveled in a direction to prevent clockwisemovement when travelling in :an upstairs direction, only, when engagedas shown in FIGURE 2. However, a `ratchet pawl 132, .at the lower end ofpawl bar 133` is held out of engagement with the ratchet teeth 131a asillustrated in FIGURE 1, and lowered into engaging position during stairclimbing, las illustrated in FIGURE 2. The pawl bar 133 is verticallyreciprocable in brackets 134, 135, and 136, being urged downwardly by aspring 137 engaging .a shoulder 138, integral with the bar 1313'. Acatch 139, on the back of rear vertical member 21 is provided to holdbar 133 in its disengaged position. However, when bar 133 lowered intoits engaged position for stair climbing, the spring 137 acts to urge thepawl 132 Adownwardly into engagement with ratchet teeth 131a.

It will be seen yfrom the foregoing description that I bave provided asimple but effective stair climbing means of light Weight, which can bevaried to suit ya variety of forms of construction Without departingfrom the spirit of the invention. Also, it will be noted that my stairclimbing mechanism not restricted to the heavy, nonfolding type of wheelchair, but may be used on wheel chairs both folding and non-folding.Indeed, in its preferred form, it is especially adapted because of itslightness in Weight Iand fol-ding features to be used in a light Weightfolding wheel chair intended for self-propulsion by the user.

Although no brake means is illustrated or described, any suitable brakemeans would be a desirable accessory.

It will be understood that my invention is not restricted to the detailsof the specific embodiment illustrated but is intended to comprehend thevariants obvious to those skilled in the art but falling within t-hescope of the following claims. For example, the simple catch d may bereplaced by any suitable latch means. There is usually sufficientflexibility in lever 95 so that it can be released from catch 101 simplyby a short backward pull, followed by a lateral deflection outward.However, more complex movable latch means, such as latch 78, illustratedin FIGURE 5, and used for holding np the arms 6 12 and 13, may be usedon arm members 22 `for locking lever in the position shown in FIGURE 4.

Having thus described the invention, 'what is claimed Ias new in`support of Letters Patent is:

ll. In an occupant-propelled folding wheel chair of the type in whichside frames are supported on folding crossbar means, each side framehaving a front caster and a rear main wheel sufiiciently large indiameter to roll over normal stair steps, and in which the occupant canpropel the chair by hand-operated means for driving said main wheels, astair climbing mechanism which includes: a pair of arms, one carried oneach of said side frames, each said arm being pivoted at its rearwardend coaXially with one of said main Wheels to permit the forward end ofsaid arm to swing between a raised and lowered position; a pair ofstair-cli-mbing wheels, one rotatably mounted on the forward end of eachof .said arms, said wheels having a diameter smaller than said mainwheels but large enough to roll over normal stair steps; a transversebrace member between said arms, said brace member being disposedsuliiciently forward to clear the side frames'of said wheel chair duringswinging movement of said arms,

'and said brace member being foldable to cooperate with the folding ofsaid wheel chair; a pair of linkage means, one on each of said sideframes, each of said linkage means being pivotally mounted on one ofsaid side frames and each said linkage means being adapted to bemanually operated by an occupant of said wheel chair to move said armsfrom a raised position to a lowered position for stair climbing; aratchet gear rotatable integrally with each of said main wheels;retractable pawl means for engaging said ratchet -gear during stairclimbing operation; and releasable latch means for holding said stairclimbing mechanism in stair climbing position.

2. A stair climbing, folding wheel chair, which includes: a pair of sideframes, each of said side frames including an arm rest member; foldableseat and back means between said side frames; a foldable transversestructure between said side frames, for holding said side frames aseat-width apart, or alternatively, in a position folded together; afront wheel means on each of said side frames; a main wheel rotatablymounted on each of said side frames near the rear thereof, each of saidmain wheels having sufficient radius to bring its rim into the vicinityof said shaft portion of said arm rests member; a manually-operateddrive means for driving said main wheel on each of said arm rests, androtatable between a drive position adjacent the rim of said main wheel,and a retracted position inboard of said arm rest member; a pair ofarms, one carried on each of said -side fra-mes, each said arm beingpivoted at the rearward part of one of said side frames to permit theforward end of said arm to swing between a raised and lowered position;a wheel rotatably mounted on the forward end of each of said arms; atransverse brace member between said arms, said brace member beingdisposed sufficiently forward to clear the side frames of said wheelchair during swinging movement of said arms, and said brace member beingfoldable to cooperate with the folding of said wheel chair; a pair oflinkage means, one on each of said side frames, each of said linkagemeans being pivotal-ly mounted on one of said side frames, and each saidlinkage means being adapted to move said arms from a raised position toa lowered position for stair climbing; lever means for operating each ofsaid linkage means, said lever means being movable from a positionforward of said drive means carrier to a position aft of said drivemeans carrier when said carrier is retracted to an unloaded position;ratchet means integral with said main wheel; and pawl means engageablewith said ratchet means for stair climbing, and retractable forhorizontal travel.

3. A stair climbing, folding wheel chair, which includes: a pair of sideframes, each of said side frames including an arm rest member with acylindrical shaft portion near the forward end; foldable seat and backmeans between said side frames; a foldable transverse structure betweensaid side frames, for holding said side frames a seat-width apart, oralternatively, in a position folded together; a front wheel means oneach of said frames; a main wheel shaft projecting laterally outwardfrom each of said side frames, at the rear portion thereof; a main wheelrotatably mounted on each of said main wheel shafts, each of said mainwheels having suflicient radius to -bring its rim into the vicinity ofsaid shaft portion of said ar-m rests member; a drive means carrier yokeincluding a sleeve rotatably carried on said shaft portion of each ofsaid arm rests; and rotatable between a drive position adjacent the rimof said main wheel, and a retracted position inboard of said arm restmem-ber; a locking means for locking each of said drive means carrier indrive position; a manually operated friction drive wheel mounted in eachof said carrier yokes for driving said main wheels; a pair of arms, onecarried on each of said side frames, each said arm being pivoted at itsrearward end on one of said main wheel shafts to permit the forward endof said arm to swing between a raised and lowered position; a wheelrotatably mounted on the forward end of each of said arms; a transverseIbrace member between said arms, said brace member being disposedsuciently forward to clear the side frames of said wheel chair duringswinging movement of said arms, and said brace member being foldable tocooperate with the fold- -ing of said wheel chair; a pair of linkagemeans, one on each of said side frames, each of said linkage means beingpivotally mounted on one of said side frames, and each said linkagemeans being adapted to move said arms from a raised position to alowered position for stair climbing; lever Imeans for operating each ofsaid linkage means, said lever means being movable from a positionforward of said drive means carrier to a position aft of said drivemeans carrier when said carrier is retracted to an unloaded position;ratchet means for preventing runaway of said wheel chair movement duringstair climbing; and a releasable latch means on at least one of said armrest members for holding said stair climbing mechanism in stair climbingposition.

4. A stair climbing, `folding wheel chair, which includes: a pair ofside lframes, each of said side frames including an arm rest member witha cylindrical shaft portion near the forward end; foldable seat and backmea-ns between said side frames; a yfoldable transverse structurebetween said side frames, for holding said side frames a seatwvidt'napart, or alternatively, in a position folded together; a front wheelmeans on each tof said side frames; a main wheel shaft projectinglaterally outward from each of said side frames, at the rear portionthereof; a main wheel rotatably mounted on each of said main wheelshafts, each of said main wheels having suicient radius to bring its riminto the vicinity of said shaft portion of said arm rest members; a pairof drive means carriers, one of said carriers being rotatably carried onsaid shaft portion of each of said side frames, and rotatable between adrive position adjcent the rim of said main wheel, and a retractedposition inboard of said arm rest member; a locking means for lockingeach of said drive means carriers in drive position; an inverted yokemember vertically adjustable within each of said drive means carriers;friction wheels rotatably mounted in said inverted yokes, and en gagingthe rims 4of said main wheels; a pair of crank means `for rotating saidfriction wheels and thereby driving said main wheels; adjustment meansbetween said drive carrier 4and said inverted yoke for adjusting thepressure of said friction wheel against the rim of said main wheel; apair of arms, one carried on each of said side frames, each said armbeing pivoted at its rearward end on one of said main wheel shafts -topermit the forward end of said arm to swing between a raised and loweredposition; a wheel rotatably mounted on the forward end of each of saidarms; a transverse brace member between said arms, said brace memberbeing `disposed sufficient forward to clear the side frames of saidwheel chair during swinging movement of said arms, and said brace memberbeing tfoldable to cooperate with the folding of said wheel chair; apair of linkage means, one on each of said side frames, each of saidli-nkage means being pivotally mounted on one of said side frames, andeach said linkage means being adapted to move said arms from a raisedposition to a lowered position for stair climbing; lever means foroperating each of said linkage means, said lever means being movablefrom a position forward of said drive means carrier to a position aft ofsaid drive means carrier when said carrier is retracted to an unloadedposition; first releasable latch means for retaining said stair climbingmechanism in stair climbing position, and second releasable latch meansfor holding it in a raised inoperative position.

References Cited in the le of this patent UNITED STATES PATENTS 838,228Williams Dec. 11, 1906 865,514 Mullenmeister Sept. 10, 1907 2,643,898Everest et al June 10, 1953 FOREIGN PATENTS 215,765 Germany Nov. 2, 1909717,241 Germany Feb. 9, 1942 137,096 Great Britain Jan. 8, 1920

1. IN AN OCCUPANT-PROPELLED FOLDING WHEEL CHAIR OF THE TYPE IN WHICHSIDE FRAMES ARE SUPPORTED ON FOLDING CROSSBAR MEANS, EACH SIDE FRAMEHAVING A FRONT CASTER AND A REAR MAIN WHEEL SUFFICIENTLY LARGE INDIAMETER TO ROLL OVER NORMAL STAIR STEPS, AND IN WHICH THE OCCUPANT CANPROPEL THE CHAIR BY HAND-OPERATED MEANS FOR DRIVING SAID MAIN WHEELS, ASTAIR CLIMBING MECHANISM WHICH INCLUDES: A PAIR OF ARMS, ONE CARRIED ONEACH OF SAID SIDE FRAMES, EACH SAID ARM BEING PIVOTED AT ITS REARWARDEND COAXIALLY WITH ONE OF SAID MAIN WHEELS TO PERMIT THE FORWARD END OFSAID ARM TO SWING BETWEEN A RAISED AND LOWERED POSITION; A PAIR OFSTAIR-CLIMBING WHEELS, ONE ROTATABLY MOUNTED ON THE FORWARD END OF EACHOF SAID ARMS, SAID WHEELS HAVING A DIAMETER SMALLER THAN SAID MAINWHEELS BUT LARGE ENOUGH TO ROLL OVER NORMAL STAIR STEPS; A TRANSVERSEBRACE MEMBER BETWEEN SAID ARMS, SAID BRACE MEMBER BEING DISPOSEDSUFFICIENTLY FORWARD TO CLEAR THE SIDE FRAMES OF SAID WHEEL CHAIR DURINGSWINGING MOVEMENT OF SAID ARMS, AND SAID BRACE MEMBER BEING FOLDABLE TOCOOPERATE WITH THE FOLDING OF SAID WHEEL CHAIR; A PAIR OF LINKAGE MEANS,ONE ON EACH OF SAID SIDE FRAMES, EACH OF SAID LINKAGE